1. Field of the Invention
The present invention relates to an image scanning and recording apparatus for use in a printer, an imagesetter, or the like for scanning an image recording medium such as a print paper or film fed in an auxiliary scanning direction with a plurality of light beams in a main scanning direction for simultaneously recording a plurality of scanning line image data on the image recording medium.
2. Description of the Related Art
There has been known a multibeam scanning and recording apparatus for simultaneously recording a plurality of scanning line image data on a photosensitive material such as a film or the like, which serves as an image recording medium that is continuously fed in an auxiliary scanning direction, with multiple beams. The multibeam scanning and recording apparatus is advantageous over conventional single-beam scanning and recording apparatus in that it can record images at a higher speed on the photosensitive material.
There are available two multibeam scanning and recording processes. One process is an n-beam noninterlaced simultaneous scanning and recording process by which images are simultaneously recorded on a photosensitive material with n beams on the noninterlaced principle. The other process is an n-beam interlaced simultaneous scanning and recording process by which images are simultaneously recorded on a photosensitive material with n beams on the interlaced principle.
FIG. 10 of the accompanying drawings schematically shows an image scanning and recording apparatus 100 based on the 4-beam noninterlaced simultaneous scanning and recording process.
As shown in FIG. 10, the image scanning and recording apparatus 100 basically comprises an image data supply unit 102 for supplying lines of data successively from a first scanning line in the sequence of scanning line numbers, 8 line buffers (LBM) 111-118 for storing respective lines of data, and a simultaneous multibeam generator 104 for simultaneously generating recording beams L1-L4 corresponding to line data supplied to channels CH1-CH4.
A data writing selector 106 is inserted between the image data supply unit 102 and input terminals of the line buffers 111-118, and a data reading selector 108 is inserted between output terminals of the line buffers 111-118 and the simultaneous multibeam generator 104. Contacts of the data writing selector 106 and the data reading selector 108 are switched by a write/read controller 110.
The write/read controller 110 successively switches the data writing selector 106 to write first through fourth lines of data into the line buffers 111-114 in synchronism with a first recording scan {at this time, the photosensitive material F fed in the auxiliary scanning direction (indicated by the arrow Y) is exposed to no recording beams because no line data are supplied to the simultaneous multibeam generator 104.
In a next recording scan, the write/read controller 110 switches the data reading selector 108 to connect the channels CH1-CH4 of the simultaneous multibeam generator 104 respectively to the line buffers 111-114. The first through fourth lines of data are simultaneously read from the line buffers 111-114 into the simultaneous multibeam generator 104, which generates and apply recording beams L1-L4 simultaneously to the photosensitive material F. At the same time that the photosensitive material F is simultaneously exposed to the recording beams L1-L4, the write/read controller 110 successively switches the data writing selector 106 to write fifth through eighth lines of data into the line buffers 111-114 for another next recording scan.
The above operation is repeated to record successive sets of four lines of image data on the photosensitive material F.
The n-beam noninterlaced simultaneous scanning and recording process as described above is able to control the writing of image data into and the reading of image data from the line buffers highly simply.
However, when n lines of image data are simultaneously formed on a photosensitive material by the n-beam noninterlaced simultaneous scanning and recording process, images reproduced from the photosensitive material sometimes suffer density irregularities and image fluctuations.
These problems could be solved by the n-beam interlaced simultaneous scanning and recording process. However, there has been established no process for writing image data into and reading image data from line buffers for the n-beam interlaced simultaneous scanning and recording process.